To support high capacity demand and new applications in evolving networks such as fifth generation (5G) wireless networks, ultra-dense networks (UDN) and moving networks (MN) are being developed. Such network architectures are challenged by high capacity demand, inter-cell interference, frequent handovers, and fast moving users, among other challenges. Technologies, such as Coordinated multipoint (CoMP) or Joint transmission (JT) CoMP, Coordinated beam forming/scheduling (CB/CS) CoMP, and multi-user multiple-input and multiple-output (MU-MIMO) based on beam forming are being proposed to alleviate such challenges. However, such CoMP and MU-MIMO schemes are closed-loop schemes, requiring channel state information (CSI) feedback, which in turn requires signaling overhead. The CSI feedback is also sensitive to channel aging and feedback error. Sparse Code Multiple Access (SCMA) is a transmission scheme with relatively low complexity receiver design and good performance. SCMA can offer high spectral efficiency by supporting overloaded systems having more connected devices or traffic than orthogonal resources. A Multi-user SCMA (MU-SCMA) scheme can also increase throughput and coverage, and support open-loop (OL) user multiplexing with low feedback overhead and with less sensitivity to channel aging and feedback error.
However, there is still a need for more efficient CoMP systems.